Re: [PATCH] cxl_test: Limit location for fake CFMWS to mappable range

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

On Mon, 9 Jun 2025 10:25:41 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> On 5/27/25 8:34 AM, Jonathan Cameron wrote:
> > Some architectures (e.g. arm64) only support memory hotplug operations on
> > a restricted set of physical addresses. This applies even when we are
> > faking some CXL fixed memory windows for the purposes of cxl_test.
> > That range can be queried with mhp_get_pluggable_range(true). Use the
> > minimum of that the top of that range and iomem_resource.end to establish
> > the 64GiB region used by cxl_test.
> > 
> > From thread #2 which was related to the issue in #1.
> > 
> > Link: https://lore.kernel.org/linux-cxl/20250522145622.00002633@huawei.com/ #2
> > Reported-by: Itaru Kitayama <itaru.kitayama@linux.dev>
> > Closes: https://github.com/pmem/ndctl/issues/278 #1
> > Reviewed-by: Dan Williams <dan.j.williams@intel.com>
> > Tested-by: Itaru Kitayama <itaru.kitayama@fujitsu.com <mailto:itaru.kitayama@fujitsu.com>
> > Tested-by: Marc Herbert <marc.herbert@linux.intel.com>
> > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>  
> 
> Applied to cxl/next
> 
> Added the config check from Alison
Thanks. Was about to send v2 but this is quicker ;)


> 
> > 
> > ---
> > I haven't given this a fixes tag because it never worked on arm64.
> > So it isn't a regression fix, and I'm not sure we want to back port this
> > which a fixes tag might well trigger.  If people want one shout and I'll
> > try and figure out what is appropriate.
> > ---
> >  tools/testing/cxl/test/cxl.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
> > index 8a5815ca870d..6a25cca5636f 100644
> > --- a/tools/testing/cxl/test/cxl.c
> > +++ b/tools/testing/cxl/test/cxl.c
> > @@ -2,6 +2,7 @@
> >  // Copyright(c) 2021 Intel Corporation. All rights reserved.
> >  
> >  #include <linux/platform_device.h>
> > +#include <linux/memory_hotplug.h>
> >  #include <linux/genalloc.h>
> >  #include <linux/module.h>
> >  #include <linux/mutex.h>
> > @@ -1328,6 +1329,7 @@ static int cxl_mem_init(void)
> >  static __init int cxl_test_init(void)
> >  {
> >  	int rc, i;
> > +	struct range mappable;
> >  
> >  	cxl_acpi_test();
> >  	cxl_core_test();
> > @@ -1342,8 +1344,11 @@ static __init int cxl_test_init(void)
> >  		rc = -ENOMEM;
> >  		goto err_gen_pool_create;
> >  	}
> > +	mappable = mhp_get_pluggable_range(true);
> >  
> > -	rc = gen_pool_add(cxl_mock_pool, iomem_resource.end + 1 - SZ_64G,
> > +	rc = gen_pool_add(cxl_mock_pool,
> > +			  min(iomem_resource.end + 1 - SZ_64G,
> > +			      mappable.end + 1 - SZ_64G),
> >  			  SZ_64G, NUMA_NO_NODE);
> >  	if (rc)
> >  		goto err_gen_pool_add;  
> 
>